Reps and SSC in basic strength

I got two questions for the forum. The first one is that, should the SSC be applied to my all of my FBE? And my second question is regarding rep range. If I can do an exercise, like a deck squat, and it takes 15 reps of it to be more challenging for me should I keep at it, or should I just add weight or do a SLS and stay at 3x5, or 5x5? Will basic strength be acquired if I start doing higher reps of exercises or does it happen only in the 3-5 rep range only?

You can use an SSC for FBE but you don't have to. I did because I was concerned about my elbow in 2011 but I should have just used a linear program for them.

Deck squats are well, too bloody easy. I don't think you need to use a SSC for any of the lower body or core movements. You can if you want, but I don't see the point.

3-5 reps is a good range as is 4/5-6/7/8. You get more hypertrophy with the latter but still work on recruiting motor units.

You can add weight with deck squats but it's troublematic IMO. You can use a vest or hold a DB/KB in front of you. In all honesty, I would rather program a barbell squat or lunge and keep the deck squats for conditioning or deck squat jumps for power.

You can also work SLS but at some point they become easy and more of a hassle to load. I do like the jumping versions though instead. I'd rather just load a box step up for single leg work, a lunge, or elevate the rear leg to focus on the work leg. Any of those are easier to load and work optimal form and not have to deal with hip flexor limitations of the pistol style SLS.

Would the hip flexor limitations also be present in atg squats?